Natural Health Advisory

Vitamin D deficiency is considered a pandemic that has increased the risk of bone diseases and many other chronic diseases. Therefore, obtaining vitamin D from foods that naturally contain it, as well as from sensible sun exposure and from supplementation, is imperative to maintain health.

Vitamin D in Fish

While few foods naturally contain vitamin D, fish is the major exception. The exact amount of vitamin D in fish varies greatly depending on the kind of fish, whether it’s wild or farmed, its diet, how it was prepared, and many other factors that researchers are still discovering. Salmon, especially wild salmon, tends to have the highest vitamin D content—sometimes as much as 1,500 IU per 3.5 oz serving.1 Sardines and mackerel are typically high in vitamin D as well. A recent analysis revealed that farmed salmon had only about 25% of the vitamin D content of wild salmon.2 Farmed trout, blue fish, swordfish and mahi had about half of the vitamin D content. Cod, grey sole, haddock, squid and clams had less than 10% vitamin D content compared to wild caught salmon.

Vitamin D from Mushrooms

Mushrooms are a fascinating, complex, and somewhat controversial natural food source of vitamin D. They are low in calories, carbohydrates, and fat, and provide important nutrients, including vitamin D, selenium, potassium, riboflavin, niacin, protein, and fiber.3

Mushrooms form vitamin D when exposed to either natural sunlight or artificial UV light.4 Wild, foraged mushrooms—both fresh and dried—are typically very high in vitamin D, whereas commercially produced mushrooms, which are grown in the dark, are not, unless they have been purposely exposed to light. Many large-scale mushroom producers in the United States are now taking these measures so that many of the mushrooms on supermarket shelves contain appreciable amounts of vitamin D.

Other Sources of Vitamin D

Other foods that naturally contain vitamin D are egg yolks, organ meats (offal), and high-fat dairy. Muscle meat (beef, pork, chicken, lamb) has some vitamin D, but the concentrations are not considerable. Egg yolks’ vitamin D concentrations are between the vitamin D values of muscle meat and organ meat. Milk and dairy products are normally quite low in vitamin D if they are not fortified with it. The highest natural values are reported in butter and cheese due to the high fat content. In the United States and Canada, milk is fortified with vitamin D, as are some bread products, orange juices, cereals, yogurts, and cheeses. The amount of vitamin D in fortified foods is generally around 100 IUs per serving.

Recent studies indicate that cooking may sometimes significantly lower vitamin D content. Canning and freezing fish does not alter its vitamin D much, nor does baking.5 Frying salmon, on the other hand, was found in one study to decrease the vitamin D by about 50%.2 The canned versions of oily fish like salmon, sardines, and mackerel can be a simple, relatively inexpensive way to get your vitamin D plus the extremely important omega-3 fatty acids EPA and DHA.

There is also some inconsistent evidence for the effects of cooking mushrooms on their vitamin D content. Vitamin D levels are maintained with frying mushrooms or making a soup, but one study found that cooking mushrooms (the technique wasn’t mentioned), considerably decreased the vitamin D content.5-7

Because of the incredible variability among foods, you can’t always depend on printed information to provide the correct vitamin D content. There is currently a renewed effort among nutrition researchers to re-measure and update this information. Nevertheless, you can use the list below, which comes from the USDA Nutrient Database and other published scientific sources, as a general guideline.8,9

• Cod liver oil: 400–1,000 IU/teaspoon
• Salmon, fresh wild caught: 600–1,000 IU/3.5 oz
• Salmon, fresh farmed: 100–250 IU/3.5 oz
• Salmon, canned: 300–852 IU/3.5 oz
• Sardines, canned: 192-300 IU/3.5 oz
• Mackerel, raw: 363-638 IU/3.5 oz
• Mackerel, canned: 250 IU/3.5 oz
• Tuna, canned: 236 IU/3.5 oz
• Shiitake mushrooms, fresh: 100 IU/3.5 oz
• Shiitake mushrooms, sun-dried: 1,600 IU/3.5 oz
• Maitake mushrooms, fresh: 786 IU/1 cup, diced
• Portabella mushrooms, grilled: 634 IU/1 cup, sliced
• Egg yolk: 20-40 IU/yolk

 

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1. J Steroid Biochem Mol Biol. 2007 Mar; 103(3-5): 642–644.
2. Arch Biochem Biophys. 2007 Apr 15; 460(2): 213–217.
3. Int J Microbiol. 2015; 2015: 376387.
4. Food Chem Toxicol. 2013 Jun;56:278-89.
5. J Food Comp Anal. 1999 Sept; 12(3):153–160.
6. Eur J Clin Nutr. 2014 Oct;68(10):1154-60.
7. Eur J Clin Nutr. 2011 Aug;65(8):965-71.
8. J Food Comp Anal. 2013 Mar;29(2):110-116.
9. J Clin Endocrinol Metab. 2011 Jul;96(7):1911-30.

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